This game is almost perfect, just needs a little bit of polish, bug-fixing and optimization but there's one thing that might be part of the design that I think could change. That being the feel of the weapons. Insurgency had a pretty great feel of the weapons. They all felt unique and like they had mass. Sandstorm on the other hand has guns that feel very much like pea shooters that sound almost exactly the same. There's basically no difference between the calibers. The guns also get very quiet once the volume is set low enough for the explosions to not cause hearing damage anymore. The recoil patterns could also use some work. Even with the PKM I don't get ANY recoil while crouched. Any gun with a foregrip and compensator likewise has no recoil.
Well that and character animations are a bit slide'y and also require more mass and generally movement could be slowed a little bit especially for low weight classes.